Alloying magnesium with ferrous metals



Patented Nov. l3, 1951 ALLOYIN G MAGNESIUM WITH FERROUS METALS Guy E. McKinney and Paul J. Motter, Canton, Ohio No Drawing. Application May 24, 1950, Serial No. 164,038

6 Claims.

The invention relates generally to a novel process for combining magnesium with ferrous metals,'and more particularly to the alloying of magnesium with iron or steel to produce a product of improved characteristics.

Pure magnesium is relatively unstable and does not occur in nature in metallic form. When strongly heated in air it oxidizes violently so as to burn with a brilliant bright light, which ac counts for its use in pyrotechnics.

However, prior to this application it has not been considered practicable or possible to alloy magnesium with iron or steel, probably because of its low melting point (1202 F.) and its tendency to burn violently at temperatures at or above 1000 F. Hence, if ure magnesium is introduced into molten iron or steel, or is associated with iron or steel at higher temperatures, it reacts violently or explodes and volatilizes instead of combining with the ferrous metal.

The Metals Handbook, 1948 edition, states on page 968that with the exception of iron, chromium, and to a lesser extent, manganese, magnesium will alloy with most of the common metals." Also, on page 1209 it is stated that magnesium is not soluble in solid iron. Most of the useful alloys of magnesium are alloys of magnesium with aluminum, with or without zinc or tin, and small amounts of manganese.

We have discovered a novel process by which magnesium can be alloyed with iron or steel in sufficient proportions to change and improve greatly the characteristics of the ferrous metal.

It is a general object of the present invention to provide a novel process of combining magnesium with ferrous metals.

Another object is to provide a novel process of producing an alloy of iron or steel and magnesium having improved characteristics.

Another object is to provide a novel process of alloying magnesium and ferrous metals, which is safe, economical and easily performed without requiring special care or skill.

A further object is to provide a novel process of alloying magnesium and ferrous metals, which produces free hydrogen as a by-product.

A still further object is to provide a novel process of alloying magnesium with ferrous metals, which enables the alloying to be performed during conventional operations of melting or refining the ferrous metals.

These and other objects are accomplished by the novel methods and products comprising the present invention, preferred embodiments of which are set forth by way of example in the following specification, the scope of the invention being defined in the appended claims forming part hereof.

Our novel process is performed in two stages; the first stage prepares the magnesium for the alloying step, and the second stage consists of the actual alloying of the prepared magnesium with the ferrous metal in a molten or highly heated condition.

In the first stage we prepare pure magnesium for subsequent alloying with ferrous metals by mixing it with pulverized fire clay. While the composition of the clay may vary somewhat, we prefer to use a clay known as semi-fire clay having the following approximate analysis:

Per cent Silica (S102) 57.22 Alumina (A1203) 25.19 Iron oxide (FEzOs) 5.59 Calcium oxide (CAO) .70 Magnesium oxide (MgO) u 1.86

Balance moisture.

The clay is first pulverized to a fine texture substantially in powder form, and then is placed over a quantity of pure magnesium in a container so as to entirely cover the magnesium. Either a closed or an open container may be used, depending upon whether it is desired to produce free hydrogen as a by-product.

If production of hydrogen is desired, a quantity of pure magnesium, preferably in solid or ingot form, is placed in the bottom of a closed container or retort having a vent tube in its upper portion, and the magnesium is completely covered and blanketed with the pulverized fire clay, the amount of fire clay being four to five times that of the magnesium by volume. The container is then heated to bring the charge up to a temperature between 1202 F. and 1500 F. and is held at that temperature long enough to completely melt the magnesium. During this heating operation, large quantities of free hydrogen are given off through the vent tube, and we make no attempt to explain this production of hydrogen, except to say that we have performed this process as described herein, and have actually produced large quantities of free hydrogen.

If the production of hydrogen is not desired, the magnesium may be prepared in an open container such as a crucible. In such case, the pure magnesium is placed in the bottom of the container and covered with four to five times as much clay by volume. It is essential that the clay be finely pulverized so that it will pack tightly around the magnesium and completely exclude air during the heating operation. Otherwise, a very violent reaction will occur. The charge in the open container is brought up to a temperature of 1202 F. to 1500 F. and maintained long enough to melt the magnesium,' and the hydrogen is allowed to escape. The crucible should not be disturbed until the temperature of the charge has dropped below 1000 F. because any agitation above that temperature may cause the mag nesium to react violently.

After the charge has been cooled 'ineitherthe open or closed container, the magnesium is in the form of a porous darkly colored mass which, as shown by analysis, contains about 14% magnesium and the balance substantially all magnesium oxide. This mass is then separated from the clay and pulverized to a fine powder. The powdered mixture of magnesium and magnesium oxide thus prepared is now mixed with a small amount of the pulverized semi-fire clay, preferably of the .approximateanalysis previously set forth, the amount of clay being about 1% to 2% by volume of the total mixture.

This mixture of a small amount of the clay with the pulverized magnesium and magnesium oxide may be called the magnesium mix, and maybe added with safety to the iron or steel with which it is to be alloyed, when the iron or steel is in a molten or highly heated condition. The magnesium mix may be added to molten steel in an open hearth or electric furnace, or it may be added tomolten cast iron or steel in a ladle. The addition of the mix into the molten iron or steel causes a mild boiling action for a few seconds which is probably due to the action of the magnesium mix as a flux or scavenger- If the magnesium mix is added to the molten metal in a ladle, the metal may be safely poured within' a few seconds and after this mild fiuxing action has terminated.

The proportion of the prepared magnesium mix to be added to the molten metal varies considerably depending upon the analysis of the molten metal and the impurities present therein. However, exact proportions are not required and the amount of the magnesium mix added may bev varied substantially without affecting the process, excepting to changethe amount of magnesium present in the final product.

By making an addition of the magnesium mix in a ladle of ordinary foundry iron in the pros portion of about 2% by weightof the magnesium mix, we have obtained cast iron containing .43% by analysis.

nesium, and on ordinary steel and mild steels we have produced a magnesium content of 33% to .51%. However, we have every reason to believe that by using larger proportions of the magnesium mix, under closely controlled furnace atmosphere and temperature conditions, substantially higher percentages of magnesium can be obtained in thermal product, and we do not wish to be limited to the foregoing percentages, as they are given merely by way of example.

Iron and steel alloyed with magnesium in accordance with our novel process in proportions of the order of the foregoing percentages of magnesium, has greatly increased corrosion resistance. increased resistance to abrasion, increased heat alloyed. with magnesium according to ourprocess Similar tests on cast iron of varying analyses have produced 28% to .67% mag- The cast iron-magnesium alloy also has has increased corrosion resistance and will take a brilliant polish.

In the foregoing description, certain terms have been used for brevity, clearness and understanding, but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such words are used for descriptive purposes herein and are intended to be broadly construed.

Moreover, the embodiments of the improved construction illustrated and described herein are by way of example, and the scope of the present invention is not limited to the exact details set forth.

Having now described the invention, the manner of operation and uses of preferred embodiments thereof, and the advantageous new and useful results obtained thereby; the new and useful methods and products, and reasonable equivalents thereof obvious to.'those skilled in the art, are set forth in the. appended claims.

We claim: v

1. The process of alloying magnesium with ferrous metal, which consists in covering pure magnesium with fire clay and heating to. melt the magnesium, cooling and separating the resulting magnesium mass and pulverizing the same, mixing the said pulverized mass with a small amount of said fire clay, and then adding said mixture to the ferrous metal in a highly heated condition.

2. The process of alloying magnesium with ferrous metal, which consists in covering pure magnesium with fire clay and heating to melt the magnesium, cooling and separating the resulting magnesium mass and pulverizing the same, mixing the said pulverized mass with one to two per cent by volume of said fire clay, and then adding said mixture to the ferrous metal in a highly heated condition.

3. The process of alloying magnesium with ferrous metal, which consists in covering pure magnesium with fire clay having an approximate analysis of 57.22% silica, 25.19% alumina, 5.59%

ferrous oxide, .70% calcium oxide and 1.86%

a ne um ide h tin he ch r e to m l h magnesium, cooling and separating the result ing magnesium mass from the clay and pulveriz-, ing the mass, mixing said pulverized mass with a small amount of said fire clay, and then adding said mixture to the ferrous metal in a highly heated condition.

4. The process of alloying magnesium with ferrous metal, which consists in covering pure magnesium with fire clay having an approximate analysis of 57.22% silica, 25.19% alumina, 5.59% ferrous oxide, .70% calcium oxide and 1.86% magnesium oxide, heating the charge to melt the magnesium, cooling and separating the resulting magnesium mass from the clay and pulveriz ing the mass, mixing said pulverized mass with one to two per cent by volume of said fire clay, and then adding said mixture to the ferrous metal in a highly heated condition.

5. The process of alloying magnesium .with

ferrous metal, which consists in covering pure magnesium with fire clay in the proportions of about four to five parts by volumeof clay to one part of magnesium, heating said covered magnesium to melt the same, cooling and separating the solidified magnesium mass from the clay, pulverizing said solidified magnesium mass and mixing it with one to two per cent by volume of, said fire clay, and then adding said mixture to.

molten ferrous metal.

6. The process of alloying magnesium with ferrous metal, which consists in covering pure magnesium with fire clay in the proportions of about four to five parts by volume of clay to one part of magnesium, said clay having an approximate analysis of 57.22% silica, 25.19% alumina, 5.59% ferrous oxide, .70% calcium oxide, and 1.86% magnesium oxide, heating said covered magnesium to melt the same, cooling and separating the solidified magnesium mass from the 10 clay, pulverizing said solidified magnesium mass and mixing it with one to two per cent by volume of said fire clay, and then adding said mixture to molten ferrous metal.

GUY E. MCKINNEY. PAUL J. MOTTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,920,934 Keen Aug. 1, 1933 2,485,760 Millis et a1. Oct. 25, 1949 FOREIGN PATENTS Number Country Date 150,367 Switzerland Jan. 2, 1932 

1. THE PROCESS OF ALLOYING MAGNESIUM WITH FERROUS METAL, WHICH CONSISTS IN COVERING PURE MAGNESIUM WITH FIRE CLAY AND HEATING TO MELT THE MAGNESIUM, COOLING AND SEPARATING THE RESULTING MAGNESIUM MASS AND PULVERIXING THE SAME, MIXING THE SAID PULVERIZED MASS WITH A SMALL AMOUNT OF SAID FIRE CLAY, AND THEN ADDING SAID MIXTURE TO THE FERROUS METAL IN A HIGHLY HEATED CONDITION. 